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March 16, 2006

Gene test helps predict lung cancer, study finds

by Sam Savage

WASHINGTON (Reuters) - A test that finds damaged genes in
the lungs of people considered at high risk of lung cancer
might be able to predict who actually develops the deadly
disease, U.S. researchers said on Wednesday.

The test is still not accurate enough for widespread use,
but could replace risky and expensive X-rays, the researchers
said.

"Short of repeatedly X-raying a person's lungs to look for
emerging tumors, there is no way now to screen people at high
risk for lung cancer, much less predict who will be diagnosed
with the cancer at a later date," said Steven Belinsky,
director of the Lung Cancer Program at the Lovelace Respiratory
Research Institute in Albuquerque, New Mexico, who led the
study.

"When perfected and validated, this kind of test holds
great promise for identifying people with lung cancer early
enough to successfully treat them," he added in a statement.

Writing in the March 15 issue of Cancer Research, Belinsky
and colleagues said their test identified 65 percent of
patients who developed symptoms of lung cancer within 18
months, but also falsely tagged 35 percent of cancer-free
people who volunteered as "controls."

The test looks at the DNA in lung cells in sputum. Certain
genes are known to be silenced or turned off in lung cancer.

Lung cancer is by far the most common cause of cancer death
in the United States and much of the world. The American Cancer
Society says that in 2006 there will be an estimated 174,470
new cases of lung cancer and it will kill 162,460 people.

Only 15 percent of lung cancer patients survive for more
than five years, in part because it causes few symptoms early
on and most people are not diagnosed until after the tumors
have spread.

"Because most people are diagnosed when their cancer is
advanced, they may not benefit from surgery, chemotherapy or
radiation, which is why median survival from diagnosis is only
13 months," said Belinsky.

"But lung tumors that can be surgically removed are
associated with a five-year survival rate of more than 60
percent."

The test looks for chemical silencing of six genes known to
be inactivated at different stages of lung cancer development
-- P16, PAX5-beta, MGMT, DAPK, GATA5 and RASSF1A. Patients with
three or more of these silenced genes in sputum had a 6.5-fold
increase risk of a lung cancer diagnosis within 18 months.

A patient testing positive for the test would receive a
follow-up bronchoscopy or an X-ray to look for tumors, Belinsky
said.